This invention relates to an outlet conventionally used on railcars for unloading a pulverant lading from within the car by gravity, a pneumatic conveying system, or the like. More specifically, this invention relates to readily taking a sample of the lading from the outlet without having to draw a large sample and in such a manner that the outlet may be readily and reliably closed after the sample is taken.
Conventionally, railcars, usually covered hopper cars, carry a variety of dry pulverant ladings. The lading may be powders such as cement or talc, or granular ladings such as grain or plastic pellets, or other dry, flowable pulverulent ladings. The covered hopper car is provided with hoppers that allow the lading to flow downwardly by gravity within the car toward one or more outlets at the bottom of the car. With some ladings, such as grain, the lading may be readily unloaded from the car merely by opening a slide gate at the bottom of the hopper and allowing the grain to flow by gravity through an open outlet into a grain transport system intake located below the railcar. However, with other ladings, such as with cement or plastic pellets, the shipper usually does not have an unloading transport system built into his siding. Here, it is generally intended that the lading not only be unloaded from the car, but also conveyed to a use or storage site some distance from where the railcar is unloaded. In these instances, it is typical for the lading to be unloaded using a so-called pneumatic unloading outlet.
Generally, a pneumatic unloading outlet includes an unloader body adapted to be secured to the bottom reaches of the downwardly sloping hopper sheets of a covered hopper car or the like. The outlet body has side sheets converging downwardly and inwardly to define an elongate discharge opening which typically extends laterally (from side-to-side) of the railcar. A product tube is positioned below the opening and is open to the discharge outlet to receive lading discharged through the opening. Typically, the outlet includes a valve selectively operable by a train attendant to regulate flow of lading from the discharge outlet into the product tube. One end of the product tube is open to the atmosphere and the other end is connected, via a hose, to a vacuum source which draws air into the open end of the product tube and through the product tube. As the air moves through the product tube, lading discharged into the product tube is entrained with the air and conveyed with the air to a storage receptacle or bin remote from the car.
A variety of railcar outlet types are known. For example, for direct gravity discharge of a lading, such as grain, a slide gate, such as is shown in U.S. Pat. No. 3,397,654, is often used. Such slide gates are relatively large plates that close off the product discharge opening in the discharge hopper and which are forcibly moved between a closed position and an open position by a gate opening and closing mechanism such as a rack and pinion drive.
Various designs for pneumatic outlets are known. A first type of pneumatic outlet uses a so-called rotating tube valve member (actually a tube with one side cut away) which is disposed within a product discharge slot of the outlet. The tube is rotatable about an axis parallel to the elongate discharge opening between a closed position (in which the cylindrical surface of the valve member blocks the flow of the lading) and an open position (in which the edge of the cut away section of the valve member rotates clear of the edge of the discharge opening and permits lading discharge into the product discharge opening). Such rotating tube pneumatic outlets are described in the co-assigned U.S. Pat. No. 3,778,114. As shown in this patent, an outlet typically has two (2) independently operable valve members, one disposed in a first half of the discharge opening and one disposed in the other half thereof. The outlet is provided with a set of two operating handles on each side of the outlet which may be operated by a train attendant to unload a lading from the railcar via the outlet. A first set of handles operates the valve member on the near side of the outlet and the other set operates the valve member on the far side of the outlet. Also as shown in this patent, a series of enlarged, spaced teeth is provided along one marginal edge of the valve member with indentations between the teeth controlling the discharge of the lading. A similar valve member construction is shown in co-assigned U.S. Pat. No. 3,194,420.
Another style of pneumatic outlet is shown in co-assigned U.S. Pat. No. 4,114,785 in which the near and far side valve members are rotary flapper gates mounted for rotation about an axis disposed generally parallel to the elongate discharge opening within and above the discharge opening for movement between a closed and an open position.
Still another style of pneumatic outlet is described in U.S. Pat. No. 4,411,560 in which a so-called rotating bar control valve is used. In a rotating bar outlet, the valve member is an enlarged diameter bar disposed within the discharge opening of the outlet for rotation about an axis parallel to, and somewhat below, the axis of the opening. With the bar valve in it closed position, the outer periphery of the bar spans across the outlet opening to block flow of lading from the discharge outlet. The valve is rotated from its closed position to bring elongated recesses in the valve member into communication with lading above the discharge outlet, and with a product discharge tube, so at least part of the lading is free to flow through the discharge outlet into the product tube.
Other pneumatic outlets are known which use horizontal slide gates movable by a mechanical operating mechanism between their closed and open positions to respectively block the flow and to permit the flow of lading from the discharge outlet into a product tube therebelow. Such slide gates described are in U.S. Pat. Nos. 4,695,207 and 5,000,358.
It is often desirable for a train attendant to take a sample of the lading in the railcar prior to unloading the lading. This can be accomplished by opening one of the hatches in the roof of the car and withdrawing a sample. However, this practice is discouraged because, first, it requires the attendant to climb onto the roof of the car and, secondly, by opening the hatch, there is a chance of contaminating the lading.
Train attendants have also taken lading samples by removing at least one of the end caps installed on the ends of the product discharge tube of a pneumatic outlet, and then operating the valve operating handles to partially open one of the valve members. This allows some of the lading to discharge from the outlet into the product discharge tube. Of course, once a small quantity of the lading has been so discharged, it is necessary for the attendant to close the valve to prevent continued flow of the lading into the product discharge tube. With certain types of pneumatic outlets, the train attendant must remove both the near and far side end caps, because these end caps are designed to prevent operations of either of the operating handles when either end cap is installed. Further, once a valve member is partially opened to withdraw the sample, it is often difficult to fully re-close the valve member. If the valve member does not fully close, lading continues to be discharged from the discharge opening of the outlet and this may result in the product tube becoming filled with lading. Of course, if the product tube becomes filled with the lading, air cannot be drawn through the product tube, thus preventing pneumatic conveying of lading from the railcar.
In an effort to overcome the problems of withdrawing a sample of lading from the outlet of a railcar, special sampling features have been incorporated into the outlets. As described in co-assigned U.S. Pat. No. 4,151,935, an arrangement was provided in a rotary flapper valve pneumatic outlet so the rotary valve member on the near side of the outlet may be moved from its fully closed position to a sampling or partially open position thereby allowing a sample of the lading to fall into the product tube. Because the end cap on the far side of the outlet need not be removed to permit the near side operating handle to be moved to the sampling position, the near valve member side could not be moved to its fully open position thus preventing the inadvertent full opening of the near side outlet valve. While this did facilitate sampling of lading via the outlet, movement of the near side outlet valve to the sampling position did release lading along the full length of the near side outlet valve (a length of approximately 31 inches) into the product discharge tube. Depending on the lading, its release, even in the partially open sampling position, may result in filling of the product discharge tube. Also, the quantity of lading released into the product discharge tube is often significantly greater than is required for a sample. The quantity of lading thus remaining in the product discharge tube now must be cleaned out. Often, it is discharged onto the railroad right of way beneath the railcar. If a toxic or hazardous lading was being sampled, the result was an environmental hazardous product spill. Still further, with such prior sampling outlets, because the entire near side outlet valve was moved to the partially open sampling position, some ladings (particularly large granular ladings) may become jammed between the edge of the outlet defining the product discharge opening and the valve member. This makes it difficult or impossible to fully re-close the outlet valve. If the outlet valve is not fully closed after taking a sample, subsequent shipping of the lading in the railcar may result in leakage of lading into the product tube so when it is desired to unload the lading, the product discharge tube would be filled with lading, thus preventing pneumatic unloading until the product discharge tube was cleaned out.
Accordingly, there has been a long-standing need for a sampling system usable with all types of outlets, which does not require opening the full length of the outlet valve to take a sample, which does not release unduly large quantities of the lading, and which does not become jammed with the lading so a valve member can be fully re-closed after a sample has been taken.